Apoptosis is a type of program cell death mechanism occurring in multi-cellular organisms that promotes cellular homeostasis by eliminating unnecessary or malfunctioning cells. Abnormalities in the apoptotic mechanism can contribute to tumorigenesis, e.g., escape of the tumor cells from the apoptotic signals, as well as resistance to anti-cancer therapies, such as, radiation therapy and chemotherapy.
Tumor cells evade the innate and adaptive immune responses (immunosurveillance) by immunoselection (selection of non-immunogenic tumor cell variants or also known as immunoediting in the mouse model) or immunosubversion (active suppression of the immune response). Zitvogel, L., J. Clin. Invest., 118:1991-2001, 2008; Koebel, C. M., Nature, 450:903-907, 2007; Zitvogel, L. et al., Nat. Rev. Immunol., 6:715-727, 2006. However, tumor cells can escape the immune control through other mechanisms involving tumor-derived factors, which may interfere with the anti-tumor immune response.
Chronic and smoldering inflammation increases the risk of neoplasia. Infectious agents are estimated to be involved in over 15% of the malignancies worldwide. Balkwill, F. et al., Cancer Cell, 7:211-217, 2005. An inflamed tissue environment can promote the development of cancer cells and immunosuppression might be a necessary component to counteract the “immunosurveillance” that protects the host against tumor development (Koebel, C. M. et al., supra). In addition, once the tumors developed, they can sustain an inflammatory state and recruit pro-inflammatory and immunosuppresive myeloid derived cells such as monocytes. An accumulation of cells from the bone marrow and other immune compartments of myeloid cells of cancer patients called “myeloid suppressor cells (MSC)” is associated with a supppressor activity on T cell activation (Galina, G. et al., J. Clin. Invest., 116:2777-2790, 2006).
As discussed above, the anti-tumoral defense, i.e., the immune system, is usually impaired in its capacity to control the presence and overgrowth of transformed tumoral cells. In addition, it also suffers from further functional impairment due to the toxicity of anti-cancer therapies.
The success of anti-cancer therapies such as radiotherapy and chemotherapy rely not only on their cytotoxic effects on the tumor cells but also on the concurrent immunocompetence during treatment. The necessary robustness of the immune function during anti-cancer treatment involves both the innate and the adaptive immune responses working in concert with anti-cancer drugs or radiotherapy. Apetoh, L. et al., Nature Med., 13:1050-1059, 2007.
Recent studies have revealed that tumor cells undergoing chemo- or radiotherapy-induced apoptosis are able to induce a potent immune response due to an increase in transient immunogenic activity. By inducing immunogenic determinants, tumor cells can transiently express “danger signals” on their cell surfaces that promote their phagocytosis by dendritic cells (DC), induce DC maturation and stimulation of the immune response. Examples of immunogenic determinants induced on dying tumor cells, include but are not limited to, heat shock proteins (HSP70 and HSP90), ligands for natural killer receptors (e.g., NKG2D), high mobility group box 1 protein (HMGB1), all of which are “danger signals” that activate the immune system. For example, HMGB1 can activate immune cells through reaction with TL4R (TLR-4). There are other danger signals, however, that fail to enhance an immune response. For example, calreticulin, which is expressed on the tumor cell surface upon induction of cell death upon anti-cancer treatment, can promote phagocytosis by DC. DC signaling by calreticulin, however, is insufficient to activate an anti-tumor immune response. Additional signaling pathways triggered by ligands of Toll-like receptors (TLRs) (probably also by other receptors) are required. Gardai, S. J. et al., Cell, 123:321-334, 2005.
The Toll-like receptors (TLRs) play a key role in the regulation of the immune system. They have the ability to recognize microbes and directly initiates specific signal transduction pathways that alert the host defenses. TLR ligands involve both non-self bacterial motifs and endogenous “danger signals.” An example of an endogenous danger signals is the high-mobility-group box 1 (HMGB1) protein, upon reaction with TLR4, is able to activate DC and generate an immune response against dying tumor cells and complement the efficacy of anti-cancer treatment, i.e., chemo- and radiotherapy (Apetoh, L. et al., Nature Med., 13:1050-1059, 2007). Because HMGB1 is released from irradiated tumor cells some hours after irradiation, it seems to be one of the major “danger signal” contributing to the immunogenicity of dying tumor cells.
Other ligands of TLR4 with the potential capacity to induce cell activation are hyaluronans (extracellular matrix), heat shock proteins (HSP), and fibronectin. HSP 70 and HSP 90 are major determinants to the immunogenicity of stressed dying cells (Tesniere, A. et al., Cell Death & Differentiation, 15:3-12, 2008).
Other danger signals released from apoptotic/necrotic cells such as uric acid, RNA, DNA, potassium (K), nucleotides are able to activate the innate immune response and thereafter an adaptive immune response.
DNA damage causes cells to upregulate expression of ligands for the NKG2D receptors expressed on NK cells and activated CD8 T cells and that can result in a cytotoxic response (Gasser, S. et al., Cancer Res., 66:3959-3962, 2006). Tumor cells tend to down regulate NKG2D ligands and thereby escape immune detection. However, during genotoxic-stress induction by anti-cancer treatment, cancerous cells upregulate NKG2D ligands and become a “visible” target for cytotoxic NK or CD8 lymphocytes.
Other danger signals expressed or released by stressed cancer cells can bind to a group of cytosolic proteins called NODs/NACHT-LRHs (NLRs) or inflammasome that activate the caspase-1 and thereby contribute to the release of pro-inflammatory cytokines such as IL-1 j and IL-18 (Martinon, F., Trends in Immunol., 26(8):447-454, 2005).
In addition, it has been reported that combination of danger signals such as HMGB1 with DNA (CpG) can induce production of interferon-α signaling through TLR4 and TLR9 (Ivanov, S. et al., Blood, 110:1970-1981, 2007).
Many of the above-mentioned molecules that represent “danger signals” can be released from tumor cells and tissues as a consequence of the anti-cancer treatment in contrast to the silent growth of tumors during long periods of time. As a consequence of tumor cell death induction by anti-cancer treatment, these tumor cells become transiently more immunogenic. However, such transient increase in immunogenicity of the tumor cells is not advantageous to the host, if at the same time, the immune cell function is suffering from the toxicity induced by anti-cancer treatments. This is because anti-cancer therapies also frequently induce myelosuppression and/or thymolysis, which, in turn, cause the immune system to miss the transient increase of antigenicity and immune stimulatory capacity of dying tumor cells during treatment. Moreover, anti-cancer therapies target tumor cells, actively dividing lymphocytes and innate immune cells, all of which are needed to mount an immune response. To overcome this dilemma, immunotherapy has been proposed to counteract the transient immunosuppression induced by anti-cancer therapies. For this very reason, anti-cancer therapies and immunotherapy have been perceived as antagonistic. van der Most, R. G. et al., Cell Death Differentiation, 15:13-20, 2008. Unfortunately, immunotherapy alone is not sufficient to protect the non-tumor dividing cells from the cytotoxic effects of anti-cancer therapy. Many types of toxicities are induced by the anti-cancer treatments on the different cell subsets of the immune system such as apoptosis, autophagy and impaired capacity of activation. Because the immune cells suffer from the side effects of anti-cancer therapy, the opportunity to profit from this window of increased immunogenicity is greatly reduced. In the process of experiencing the side effects of cancer therapy-induced apoptosis, antigen-presenting cell function, innate cell killing and antigen specific tumor cell killing are also affected in the host. The period of transient enhancement of immunogenicity in cancer-therapy-induced cell death represents an opportunity for the immune system to recover the control on the transformed cells and keep in check the remaining viable tumor cells. To profit from this window of enhanced antigenic or immunogenic expression, the present invention provides methods and immunonutritional compositions, which when applied and administered to a patient undergoing stress-induced apoptotic cancer therapy, would further enhance their innate immune response and anti-tumor immune response. Therefore, by nutritional conditioning of the immune system (via immunonutrition) around the cycles of chemo- and radiotherapy treatment, acute immune toxicity induced by such treatment can be corrected and which, at the same time, corresponds paradoxically to a moment of enhanced immunogenicity of the tumor cells.
Tumor cells undergoing the cellular stress and expressing “danger signals” and death induced by the anti-cancer treatment can become a more “visible” target to the innate response against and thereby be more easily attacked by innate effector cells, such as natural killer (NK) cells, natural killer T (NKT) cells, gamma-delta (γδ) T cells and killer dendritic cells (KDC). Pillarisetty, V. G. et al., J. Immunol., 174:2612-2618, 2005. In addition, activated DC can stimulate a tumor antigen-specific cytolytic T cell response. Activation of the innate immune responses can be enhanced by administering exogenous agents or adjuvants, ligands for co-stimulatory proteins, cytokines, or drugs. For example, nucleic acid recognition (e.g., double stranded RNA, nucleotides) by DC through endosomal located TLRs (TLR3, TLR9) can help the DC activation and subsequently an antigen-specific anti-tumor immune response. Blattman, J. N. et al., Science, 305:200-205, 2004. Another example, CpG, an oligonucleotide, can enhance the capacity to attain the NK-like activity by DC and can increase the status of DC activation and prevent thereby the “tolerogenic” signals generated by the tumor and the conditioned immune cells by the tumor like alternatively activated macrophages.
There are many other nutrients that have shown activities to increase innate immune function (immunonutrients). For example, some non-pathogenic probiotic bacteria have the capacity to activate macrophages, dendritic cells and natural killer (NK) cells which would lead to the improvement of antigen presentation and innate destruction of tumor cells. As mentioned above, nucleotides, acting as surrogate signal of danger, can activate the immune system. Stimulation of immune reactivity by DNA, RNA and CpG has been confirmed by several studies.
Arginine and citrulline, as well as branched-chain amino acids, can stimulate protein synthesis through mTOR signaling, which, in turn, prevents the autophagic process on immune cells that may be induced by the stress of anti-cancer treatments. Glutamine can increase the innate cytolytic activity of NK, macrophages and killer dendritic cells can contribute to the antigen-specific cytolytic activity of CD8+ T cells against tumor cells. Some bacterial or yeast molecular patterns can stimulate the activity of innate lymphocyte populations, e.g., NK, NKT and gamma-delta T cells, with cytotoxic activities against tumor cells and promote enhanced activation of the antigen-presenting cells to process and present tumor antigens to CD4+ and CD8+ T cells.
Several nutrition formulas supplemented with one or more of these immunonutrients having immune-modulating properties, have been developed.
U.S. Pat. No. 6,210,700 generally describes an improved immunomodulatory therapy for enhancement of depressed host defense mechanisms and improving allograft survival rates which includes the use of omega-9 unsaturated fatty acids to alter the immune response associated with organ transplantation It is administered, optionally, in conjunction with an immunomodulatory diet comprising arginine and its salts, or metabolic precursors of arginine, together with an immuno-suppressive treatment comprising the administration of cyclosporine or other immuno-suppressants and optionally, with or without a donor specific transfusion. An especially preferred source of the omega-9 unsaturated fatty acids is canola oil.
U.S. Pat. No. 5,330,972 generally describes that apoptosis of CD4 cells in a person infected with the human immunodeficiency virus may be impeded by enterally feeding to the infected person with a nutritional product that contains soy protein hydrolysate having a degree of hydrolysis in the range of about 14 to 17, and a molecular weight partition, as determined by size exclusion chromatography, wherein 30%-60% of the particles have a molecular weight in the range of 1500-5000 daltons. The nutritional product also contains a source of intact protein and dietary fiber. The nutritional product has a ratio, by weight, of n-6 to n-3 fatty acids of about 1.3:1 to 2.5:1.
U.S. Pat. No. 5,576,351 relates to the treatment of an impaired human immune response or to reduction of the severity of degradation of the human immune response by the administration of arginine or ornithine, or a functional analog of arginine or ornithine, or mixtures thereof, to humans suffering from an impaired immune response or at risk of suffering an impaired immune response. Such treatment is provided by enterally administering compositions supplemented with arginine or ornithine, or functional analogs of arginine or ornithine, or parenterally administering amino acid solutions supplemented with arginine or ornithine, or functional analogs of arginine or ornithine, to the patient.
U.S. Patent Application Publication No. 2008/0231525 describes a nutrient composition that is parenterally delivered to a critically ill patient or for the purpose of improving mitochondrial function. The nutrient composition includes a combination of a glutamine precursor molecule and an anti-oxidant, e.g., selenium, vitamin C, zinc, vitamin E, and beta-carotene.
U.S. Patent Application Publication No. 2005/0090451 generally describes a method of protecting non-mucosal tissue against damage from radiation therapy via the administration of a composition that includes a therapeutically effective amount of glutamine or a pharmaceutically acceptable salt.
U.S. Patent Application Publication No. 2005/0238660 A1 relates to methods and compositions of an immunostimulatory nucleic acid in combination with other therapeutic formulations such as oil-in-water emulsions. The combination of therapeutics is administered to non-human subjects in various dosages or at various time schedules for the treatment of disorders such as disease and cancer.
However, none of the prior art cited, as discussed herein, describes or suggests the addition of the immunonutrients to cancer patients undergoing cancer therapy-induced apoptosis and/or necrosis, at a time when the dying tumor cells are undergoing the window of enhanced antigenic or immunogenetic expression. After all, the goal of immunonutrition should be to counter balance tumor-induced immune tolerance during anti-cancer therapy-induced cell death or damage, thereby tipping the balance of host-tumor balance towards the reinforcement of the host defenses. At the same time, immunonutrition, when provided to cancer patients, can enhance antigen-presenting cell function and innate cell destruction of the transformed cells and antigen-specific tumor cell destruction. In the end, the major target of immunonutrition, as proposed herein, should be on the non-tumoral cells that are transiently weakened by anti-cancer therapy treatment.
Based on the above, there is a need for methods and immunonutritional compositions that can be formulated for preventing the impairment of the immune function of cancer patients during the anti-cancer treatment to attain a better efficacy of treatments. There is also a need for methods and immunonutritional compositions, which when applied and administered in combination with anti-cancer therapies would produce less adverse side effects to cancer patients. More importantly, there is a long felt need for methods and immunonutritional compositions that can be employed at the time when dying tumor cells undergo a window of immunogenicity, which act in concert with the prescribed anti-cancer therapy and further enhance innate and adaptive immune processes of the host to enhance tumor cell killing. There is also an urgent need for methods and immunonutritional compositions that can preserve the normal physiology of the immune cells and other hemopoeitic cells (i.e. bone marrow) and rescue their immunocompetence that were damaged by anti-cancer therapy.
The methods and compositions and the means of accomplishing each of the above needs, as well as others, will become apparent from the detailed description which follows thereafter.